I agree with cleaninLI. If he says he wants to do OP and isn't open to Inpatient then I would worry. My sister went to a 30 day OP program after a 7 day detox and relapsed before the 30 days. That was in June and now she won't do rehab and is on the run.
Addicts tell you what they can to buy time and get you off their backs. Stay focused and don't back down. They have got to really want it and it will be an everyday struggle for the rest of their of their lives.